There exists a multitude of products which are designed to conform to individual body parts. Examples of these products are demonstrated in a wide array of settings, from personal daily usage such as footwear, chair seats, lumbar supports, pillows and beds to sporting equipment such as shin guards, helmets, mouth guards and other protective gear.
The purpose of these products is generally to provide the benefits of comfort, support, protection and shock absorption to the user. These products can be generic or, more preferably, can be customized to fit a particular individual's body part.
There have been a number of approaches to providing custom-fitting insoles for footwear. One approach over the past twenty years with mixed success utilizes foams, silicone foams and silicone. The raw materials however are generally expensive, difficult to use and may generate hazardous fumes. Furthermore, the resulting products are fitted by a professional sales person and can only be fitted once. Additionally, since these products are not remoldable and can not be reused, if an error is made in the fitting process, the product is discarded and the process restarted.
In an alternative approach, a layer of a thermoplastic material is provided for in a shoe, sandal, or insole. The thermoplastic material is heated, thus softening it, and the individual desiring to wear the footwear steps into the shoe and makes an impression. The material then cools, retaining the impression of the foot. See U.S. Pat. Nos. 3,641,688; 4,413,429; 4,433,494; 4,503,576; 3,895,405; and 4,901,390. The content of all the foregoing patents is incorporated herein by reference. However, most of the foregoing thermoplastic materials are foams which have poor compression set properties and break down and compress over time, others are non-foams which are unduly hard, have unduly high specific gravity, and have insufficient elasticity and resilience. In addition, body heat itself can soften or at least increase the flexibility of the pad, thereby decreasing the effectiveness of the protection offered by the pad.